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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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* published by the Free Software Foundation. Oracle designates this
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*
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* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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package com.sun.source.util;
import com.sun.source.tree.*;
/**
* A TreeVisitor that visits all the child tree nodes, and provides
* support for maintaining a path for the parent nodes.
* To visit nodes of a particular type, just override the
* corresponding visitorXYZ method.
* Inside your method, call super.visitXYZ to visit descendant
* nodes.
*
* @apiNote
* In order to initialize the "current path", the scan must be
* started by calling one of the {@code scan} methods.
*
* @param the return type of this visitor's methods. Use {@link
* Void} for visitors that do not need to return results.
* @param the type of the additional parameter to this visitor's
* methods. Use {@code Void} for visitors that do not need an
* additional parameter.
*
* @author Jonathan Gibbons
* @since 1.6
*/
public class TreePathScanner extends TreeScanner {
/**
* Constructs a {@code TreePathScanner}.
*/
public TreePathScanner() {}
/**
* Scans a tree from a position identified by a TreePath.
* @param path the path identifying the node to be scanned
* @param p a parameter value passed to visit methods
* @return the result value from the visit method
*/
public R scan(TreePath path, P p) {
this.path = path;
try {
return path.getLeaf().accept(this, p);
} finally {
this.path = null;
}
}
/**
* Scans a single node.
* The current path is updated for the duration of the scan.
*
* @apiNote This method should normally only be called by the
* scanner's {@code visit} methods, as part of an ongoing scan
* initiated by {@link #scan(TreePath,Object) scan(TreePath, P)}.
* The one exception is that it may also be called to initiate
* a full scan of a {@link CompilationUnitTree}.
*
* @return the result value from the visit method
*/
@Override
public R scan(Tree tree, P p) {
if (tree == null)
return null;
TreePath prev = path;
path = new TreePath(path, tree);
try {
return tree.accept(this, p);
} finally {
path = prev;
}
}
/**
* Returns the current path for the node, as built up by the currently
* active set of scan calls.
* @return the current path
*/
public TreePath getCurrentPath() {
return path;
}
private TreePath path;
}